With the development of digital content technologies and the development of data transmission media, an exchange of data and an amount of information have been suddenly increased. Generally, various types of digital contents such as movie, music, document, picture, and the like, are produced and shared and rapidly distributed by the Internet, P2P, web hard, such that contents can be easily acquired. A social problem due to the sharing of the contents is the very infringement of right of a copyrighter caused by the illegal sharing of digital contents having a copyright. Due to examples of the infringement of copyright on the digital contents, technologies such as digital rights management (DRM), watermarking, finger printing, and the like, have been used to protect a right of a copyright holder and prevent a damage of a user. However, when copyrighted materials such as CDs, DVDs, and books are digitalized and shared by digital devices, a right of a copyright holder is not protected well and a damage of a user is not prevented.
In particular, in the case of comics, real publications are produced into digital contents and are mutually shared among users by illegal duplication and a copying process using a high-specification scanner or digital camera and therefore, a right of a copyright holder is frequently infringed.
Recently, technical protective measures for protecting a copyright is obligatory. Thus, in most online service providers (OSPs), a filtering technology using content recognition has been applied to music or video contents. Filtering is a technology of monitoring and filtering sound sources or videos that are illegally distributed using features, content deoxyribonucleic acid (DNA), or digital finger printing.
While the protective technology for monitoring and filtering illegal contents is not applied to comic contents due to the absence of related technologies.
Today, most sites serving comic contents through the Internet do not have an apparatus for preventing a simple illegal duplication such as screen capture, and the like, and only some thereof relatively safely protect a copyright of contents using an encryption technology or a capture prevention technology. However, when decrypting the encrypted content or bypassing the capture prevention technology, the comic contents may be illegally stored and distributed.